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Many small molecules had not become part of any cell. They were floating free in the waters of the Earth. This was the food which the first cells ate. Once inside the cell some small molecules were built up into large molecules such as proteins, so the cell grew bigger. Others were broken down into smaller molecules such as acids or alcohols to release chemical energy. This process is called fermentation. The small molecules were sent out of the cell as waste products.
Fermentation is still important on earth today, and is used by people in several ways. Our cells use fermentation as the first step in breaking down sugars. Normally the end result of fermentation, such as lactic acid, is further broken down by the process of respiration to produce carbon dioxide and water. However, if we exert ourselves for example by running, lactic acid builds up in our muscles and causes pain. We use the fermentation of other cells in various ways. Yeast break down sugars into alcohol, and we use this to make beers, wines and spirits. Fermentation releases carbon dioxide and we use this to cause bubbles in bread. Lactic acid producing bacteria are also used in the cheese making process, as well as making buttermilk, sour cream and yoghurt. |
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Useful Links |
Biological Environment > Fermentation
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This site tells the story of the history of the universe. Click Earlier and Later to follow the story.
Note: Many facts have been simplified to make them easier to understand.
Click here to read Time Crystal, history of the Universe as sci-fi fantasy romance!
Note: Many facts have been simplified to make them easier to understand.
Click here to read Time Crystal, history of the Universe as sci-fi fantasy romance!
